One of the most important properties of fused quartz is its extremely low coefficient
of expansion: 5.5 x 10-7 mm °C (20-320oC). Its coefficient is 1/34 that of copper and
only 1/7 of borosilicate glass. This makes the material particularly useful for optical flats,
mirrors, furnace windows and critical optical applications which require minimum sensitivity
to thermal changes.

Mechanical properties of fused quartz are much the same as those of other glasses. The
material is extremely strong in compression, with design compressive strength of better
than 1.1 x 109 Pa (160,000 psi).